Research On Planar EBG And DGS For Power Supply Noise Suppression In High-speed Circuit Systems

With increasing clock speed,power integrity(PI),signal integrity(SI)and electromagnetic interference(EMI)have become the dominant problems that stop the further development of high speed circuit systems and PI should not be ignored by any high-speed circuits.A traditional solution for PI problem is to employ amounts of decoupling capacitors of different types between the power and ground boards.However,those decoupling capacitors cannot suppress the power supply noise with continuously increasing frequency because of the intrinsic self-resonance.So the electromagnetic bandgap(EBG)structure and the ground defected structure(DGS),which can operate at microwave frequencies easily,have drawn much attention and been researched as the potential techniques of power supply noise suppression.Nonetheless,they also have a few of drawbacks such as large sizes and causing SI problems.This thesis makes a rigorous study about the application of planar EBG and DGS in power supply noise suppression,mainly exploring new EBG designs with a smaller lower cutoff frequency(i.e.smaller size)and solutions for SI improvement.Firstly,starting from the basic structures of EBG and DGS,this thesis analyzes their transmission performance by using the equivalent circuit model(ECM)and the theory of transmission line.Bandgap features of EBG are extracted directly with the scattering parameters(S-parameters)and influences of structure parameters on bandgap are discussed theoretically using the ECM.As for the DGS,values of corresponding components of ECM are extracted precisely with S-parameters.With the part of ECM analysis,theoretical foundation and guideline are provided for the design and modification of EBG and DGS.Secondly,two advanced planar EBG structures,which experience smaller lower cutoff frequency,are presented.The proposed structures realize miniaturization by loading spiral-shaped bridge and lengthening trace of connecting bridge based on typical UC-EBG and L-EBG respectively.Numerical simulation demonstrates that lower cutoff frequencies of advanced UC-EBG and advanced L-EBG decrease by 31.3% and 46.3% respectively.In addition,considering that planar EBG trends to cause SI problems because of discontinuity,techniques of localized reinforced ground trace and complementary EBG are proposed to improve the signal transmission quality.Finally,a spiral-shaped DGS is presented and analyzed for power supply noise suppression.Measurement and simulation make a good agreement that proposed DGS owns many advantages such as small lower cutoff frequency,wide suppression band and simple structure.Besides,compared with planar EBG,DGS maintains much bigger continuity of planes thereby guaranteeing good SI.In the end of this thesis,transmission behaviors of different signal lines are discussed and a few of useful suggestions are given for wiring on DGS boards.